A common problem for designers is the provision of an adjustable, rotational-relationship between two structural members. It can be especially important that this relationship between two structural elements be selectively adjustable and that the structure provides the ability to lock and unlock any selected angle at will. Various solutions are seen. The foot rests used in the seats of commercial aircraft are a typical application as is a means to adjust the rotational position of an arm relative to a frame from which it is fixed. Some examples of mechanisms from the prior art follow:
Geyer, in U.S. Pat. No. 5,699,698, teaches a logarithmic cam mounted on a shaft offset to permit unlocking.
Erickson, in U.S. Pat. No. 5,482,417, provides a self locking mechanism uses a shaft mounted cam with the cam surfaces on the periphery of a centrally opened cylinder.
Barnes, in U.S. Pat. No. 5,530,999, teaches an axial locking device with locking balls wherein slider teeth push against rotor teeth which are spring loaded.
Thumm, in U.S. Pat. No. 4,202,227, shows a mechanism in which an axial face of a driving ring has cam surfaces engageable with cam surfaces on a moveable locking ring which has gear teeth mating with teeth on a flange.
All of the above are serviceable solutions to the basic problem. All, however, lack the simplicity which is one object of the instant invention. Other objects of this invention are provision of a positive lock against torque applied to the members while maintaining a low unlocking force suitable to manual operation, and a relatively low cost to fabricate.